Track the next rank in each arithmetic run.
Calculation begins with Ace, 2, 3, and 4 on four foundations. They then advance by one, two, three, and four ranks respectively, wrapping after King. Suit does not restrict foundation play.
Last updated: September 2026
Look one step ahead in every lane
The first foundation needs 2 after its Ace; the second needs 4 after its 2; the third needs 6 after its 3; the fourth needs 8 after its 4. A 4 can serve the first or second foundation depending on their current positions. When a stock card fits more than one lane, consider which choice exposes a waste top or creates another immediate rank match.
The remaining 48 cards are drawn one at a time. A card can go straight to a legal foundation or to one of four waste piles. Only each waste top can later build. Before placing a card on waste, compare the card it will cover with the next ranks needed by all four lanes. A near-term card covered by a card needed much later can stall progress.
Use the four waste piles as access tools
There is no stock redeal in Calculation. An empty pile gives a card its own route to a foundation, but the four slots fill quickly. A pile with a card likely to play soon may be a poor place for another card, even if both have similar ranks; their foundation steps may differ.
For example, a 6 at the top of waste can immediately follow 3 on the step-three foundation. Covering it with a Jack delays that move until the Jack finds a legal lane. If a different waste pile has a top card needed later, placing the Jack there may preserve the 6.
Musical: one waste and two redeals
Musical also uses step-one through step-four foundations, but their starting cards are 2, 4, 6, and 8. Four signs sit outside the buildable foundations. Its stock draws onto a single waste pile; the exposed waste top may build when its rank matches a foundation's next arithmetic step. You cannot choose among four waste destinations as in Calculation.
When Musical's stock empties, you may turn the waste over for another pass, at most twice. Before drawing over a playable waste top, use it if its foundation placement advances access. Because all cards share one waste pile, the recycle order matters more than pile assignment.
Another interval puzzle
Imaginary Thirteen has eight step sizes, two decks, and four waste piles. Its marker and foundation rules warrant a separate guide.